> On Nov 14, 2016, at 5:22 PM, Shaohua Li <shli@xxxxxxxxxx> wrote:
>
>> The following detailed explanation is copied from the raid5-cache.c:
>>
>> /*
>> * raid5 cache state machine
>> *
>> * With rhe RAID cache, each stripe works in two modes:
>> * - caching mode
>> * - writing-out mode
>
> 'mode' is quite confusing here. it always remainders me r5c_journal_mode. can
> you use state?
I am not very sure whether state is the best name here. Maybe we can use "phase"?
>> + * Note: when the array is in write-through, each stripe still goes through
>> + * caching mode and writing-out mode. In such cases, this function is called
>> + * in r5c_handle_stripe_dirtying().
>> + */
>> +static void r5c_make_stripe_write_out(struct stripe_head *sh)
>> +{
>> + struct r5conf *conf = sh->raid_conf;
>> + struct r5l_log *log = conf->log;
>> +
>> + if (!log)
>> + return;
>> + WARN_ON(test_bit(STRIPE_R5C_WRITE_OUT, &sh->state));
>> + set_bit(STRIPE_R5C_WRITE_OUT, &sh->state);
>> +}
>> +
>> +/*
>> + * Setting proper flags after writing (or flushing) data and/or parity to the
>> + * log device. This is called from r5l_log_endio() or r5l_log_flush_endio().
>> + */
>> +static void r5c_finish_cache_stripe(struct stripe_head *sh)
>> +{
>> + struct r5l_log *log = sh->raid_conf->log;
>> +
>> + if (log->r5c_journal_mode == R5C_JOURNAL_MODE_WRITE_THROUGH) {
>> + BUG_ON(!test_bit(STRIPE_R5C_WRITE_OUT, &sh->state));
>> + /*
>> + * Set R5_InJournal for parity dev[pd_idx]. This means parity
>> + * is in the journal. For RAID 6, it is NOT necessary to set
>> + * the flag for dev[qd_idx], as the two parities are written
>> + * out together.
>> + */
>> + set_bit(R5_InJournal, &sh->dev[sh->pd_idx].flags);
>
> if this flag is only for pd_idx disk and you are using it to determine the
> stripe data is in journal, why not make it a stripe flag?
R5_InJournal is used in multiple place in the next patch. Using it here will
save us a stripe flag.
Thanks,
Song
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